Various methods of producing single crystal castings are known. Generally, these methods require a temperature of about 400.degree. F. temperature gradient above the melting point of the alloy to be grown in a single crystal structure. Such a temperature gradient is needed so that a section of the casting can be cooled below the melting point of the alloy and solidified slowly so that small layers build up duplicating and taking on the crystal structure of the previous solidified layer. Nickel-aluminide (NiAl) in a 50/50 atomic percent ratio would be a desirable alloy for a variety of structures including gas-turbine blades or components. However, NiAl(.beta.'), i.e., in a 50/50 atomic weight percent ratio, has a melting point of 2980.degree. F. (about 1638.degree. C.).
Unfortunately, commercially available ceramic casting mold shells and cores turn to glass at about 3000.degree. F. In order to produce a single crystal structure using NiAl(.beta.'), the casting mold and cores would have to be able to withstand a temperature of about 3400.degree. F. Thus, conventional methods of casting using molds and ceramic cores are not suitable for making a single crystal casting of NiAl(.beta.').
Thus, it would be desirable to have a method of producing single crystal castings of NiAl(.beta.').